fontconfig: fix build

As of 3.1, gperf hash/lookup functions take 'size_t' length parameter
instead of 'unsigned int'. Unfortunately, the upstream fix [1] actually
breaks compilation with it.

[1] https://cgit.freedesktop.org/fontconfig/commit/?id=9878b306f6c673d3d6cd9db487f67eb426cc03df

srcpkgs/fontconfig/template

@@ -4,7 +4,7 @@ version=2.12.3
 revision=1
 build_style=gnu-configure
 configure_args="--disable-static --enable-docs --with-cache-dir=/var/cache/$pkgname"
-hostmakedepends="pkg-config"
+hostmakedepends="pkg-config gperf"
 makedepends="expat-devel zlib-devel freetype-devel"
 conf_files="/etc/fonts/fonts.conf"
 short_desc="Library for configuring and customizing font access"
@@ -14,6 +14,10 @@ license="MIT"
 distfiles="${FREEDESKTOP_SITE}/${pkgname}/release/$pkgname-$version.tar.bz2"
 checksum=bd24bf6602731a11295c025909d918180e98385625182d3b999fd6f1ab34f8bd
 
+pre_build() {
+	# trick to regenerate hash functions :-)
+	rm -f src/fcobjshash.h
+}
 post_install() {
 	if [ "$CROSS_BUILD" ]; then
 		sed -i 's,\(Cflags: -I${includedir}\).*,\1,g' ${DESTDIR}/usr/lib/pkgconfig/fontconfig.pc